Detonator



Patented Aug. 2, 1938 UNITED STATES DETONATOR| FOR EXAMPLE,

DETONA'I'OR BLASTING Leon Rubenstein, Saltcoats, Scotland, assignor toImperial Chemical Industries Limited, a corporation of Great Britain NoDrawing. Application February 9, 1937, Se

rial No. 124,928. 14, 1936 7 Claims.

This invention relates to detonators and more particularly to chargestherefor.

This invention has as an object to devise a new and improved charge fordetonators. A further object is to devise a charge which will beparticularly valuable as a base charge in a detonator of the typedescribed above. Further objects will appear hereafter.

These objects are accomplished by the following invention. I have foundthat I can use as a base charge guanyl azide picrate (diazoguanidinepicrate) with or without admixture of other suitable base chargeingredients, for example tetryl. The detonator shell may be formed fromcopper, aluminum or any suitable copper or aluminum alloy. Guanyl azidepicrate has a sufiiciently high brisance to enable it to be used formodern blasting practice and it is not so easiy ignited by shock orfriction as substances such as mercury fulminate or lead azide. Theinvention further includes a charge for a detonator comprising a primaryinitiating composition, e. g., a mixture of lead azide and leadstyphnate, and a base charge comprising guanyl azide picrate.

Guanyl azide picrate possesses excellent storage properties and has theproperty of running freely, which facilitates the loading of thedetonator. It can also be corned or granulated in the usual fashion. Itbinds together satisfactorily under the pressures which are normallyemployed in loading detonators.

The following examples illustrate but do not limit the invention.

Example 1 25 centigrams of guanyl azide picrate are pressed at 162 lb.per sq. inch into an aluminum detonator tube of 6 mm. diameter and 35mm. length. 35 centigrams of a mixture of 30, parts by weight of leadstyphnate and 70' parts by weight of lead azide are then pressed intothe detonator above the picrate base charge at the same pressure. Anelectric fuse containing a fusehead primed with leadmononitroresorcinate is inserted and crimped into position in thedetonator. On testing this electric detonator on a lead plate of 4 mm.thickness, such as is used for testing detonators, a deep indentationand perforation of the plate is produced when the detonator is fired,the fusehead being ignited by a current of 0.5 amp. passed through itfor not over 0.05 sec. by means of suitable connecting wires.

Example 2 25 centigrams of guanyl azide picrate are pressed at 176 lb.per sq. inch into a copper deto- In Great Britain February nator tube of6 mm. diameter and 35 mm. length. This base charge is followed by aprimingcharge of 40 centigrams of a mixture consisting of 90 parts byweight of mercury fulminate and parts by weight of potassium chlorate. Aperforated copper cap 8 mm. in length is inserted and pressed intoposition under a load of 176 lb. per sq. inch. A length of fuse iscrimped into the detonator. When placed on a lead plate of 4 mm.thickness, and fired by means of the fuse, the detonator produces anindentation in the lead plate similar to that formed when a base chargeof tetryl is employed instead of guanyl azide picrate.

This invention is a valuable contribution to the art as guanyl azidepicrate combines both the high brisance necessary for use in a detonatorwith its property of not being easily ignited by shock or friction, itsexcellent storage and free running properties make it peculiarlysuitable for detonators as does its property of binding under pressure.

It is to be understood that I do not limit myself to a detonator inwhich there is both a primary and a secondary charge. I prefer to use aprimary charge when making a detonator with guanyl azide picrate but Iclaim the use of it in detonators whether a primary charge is used ornot.

Thus the preferred form of my detonator comprises an initiator such asan electric fusehead or a deflagrating charge comprising lead mononitroresorcinate, copper acetylide or basic lead dintrocresylate (U. K. Appn.7403/36) or lead picrate or a lead thiocyanate-chlorate mixture and aprimary charge comprising mercury fulminate or lead azide or leadazide/lead styphnate mixtures and a base charge of guanyl azide picratewith or without other suitable base charge ingredients.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodimentsthereof except as defined in the appended claims.

I claim:

1. A blasting cap wherein the base charge comprises guanyl azidepicrate.

2. A blasting cap comprising a metal container, a primary charge, and abase charge comprising guanyl azide picrate.

3. The blasting cap according to claim 2 wherein the container is ofcopper and the primary charge comprises mercury fulminate and potassiumchlorate.

2 azaaaea 4. An electric blasting cap comprising a metal container, anignition charge. a primary charge, and a base charge which comprisesguanyl azide picrate.

5 5. The electric blasting cap according to claim 4 wherein thecontainer is of aluminum and the primary charge comprises lead azide andlead styphnate.

8. The electric blasting cap according to claim 4 wherein the ignitioncomposition comprises lead mononitro-resorcinate.

7. A blasting cap comprising an initiator, a

' primary charge and a base charge which com- 5 prises guanyl azidepicrate.

LEON RUBENSTEIN.

